For people with prediabetes, small changes in daily habits can make a meaningful difference. In a recent study from Penn State, researchers found that eating pistachios as a bedtime snack changed gut bacteria in ways that could support better health.
The study, published in Current Developments in Nutrition, followed 51 adults with prediabetes who tried two different nighttime snacks for 12 weeks each: one group ate a traditional carb-based snack, like a slice or two of whole grain bread, while the other ate about 2 ounces of pistachios. After each phase, researchers compared stool samples to see how the snacks affected gut bacteria.
“Pistachios seem to be able to meaningfully shift the gut microbial landscape in adults with prediabetes, especially when consumed as a nighttime snack,” said Kristina Petersen, Ph.D., associate professor of nutritional sciences at Penn State.
People who ate pistachios had more of the types of gut bacteria that are linked to better digestion and reduced inflammation. These bacteria also help make compounds that support the lining of the gut and may help with blood sugar regulation.
The pistachio snack also lowered levels of certain bacteria that are considered less helpful, including some that may contribute to harmful byproducts or break down beneficial antioxidants found in plant foods.
“These microbiome changes may offer other long-term health benefits, potentially helping to slow the development of type 2 diabetes or to reduce systemic inflammation, which we hope to explore in future research,” Petersen said.
For people with prediabetes, it’s common to be told to eat a small carb-based snack before bed to help manage blood sugar overnight. According to the study’s lead author, Terrence Riley, Ph.D., pistachios may offer a similar effect while also supporting gut health.
“A common dietary recommendation for individuals with prediabetes is to consume a nighttime snack consisting of 15 to 30 grams of carbohydrates to help regulate overnight and morning blood glucose levels,” Riley said. “As an example, you could eat one or two slices of whole grain bread.”
Because each participant in the study tried both snack types, researchers were able to directly compare how the different foods affected the same people. While more research is needed, the results suggest that swapping out a standard snack for pistachios may be a simple way to support gut health for those trying to prevent type 2 diabetes.
This study was supported by the American Pistachio Growers, the National Institutes of Health through Penn State’s Clinical and Translational Science Institute, the National Science Foundation and the Howard Hughes Medical Institute through Juniata College. Funders were not involved in study design or interpretation.